Tridentate 1,4,7-triazacyclononane

A few other complexes with N-N coordinating atoms have been tested as olefin polymerization catalysts. The aminopyridinato complex 181 is only able to oligomerize propylene and 1-butene (Mn < 3500) with low activity.1222 The /3-diketiminato Zr complex 182 exhibits moderate ethylene polymerization activity ( 50gPE(mmol M)-1 h-1 bar-1), but molecular masses were disappointingly low (Mn up to 30000).1117 Finally, at 100°C, the MAO-activated Ti complex 183, with a tridentate triazacyclononane ligand, yields PE with very high activity (104gPE(mmol M)-1 h-1 bar-1) but rather low molecular masses and broad polydispersity (Mn = 39500 Mw/Mn = 7.0).1223... 

In addition to chelate complexes, the cyclic amine 1,4,7-triazacyclononane will complex to platinum(II) and (IV). The hexacoordinate platinum(IV) complexes are bonded to two molecules of the tridentate ligand, but platinum(II) complexes with the ligand monodentate and bidentate.988 Also the formation of platinum(II) ammine complexes from chloride complexes is a reversible process. The rate constants decrease as the basicity of the leaving amine increases.989... 

The thermodynamic stability of the binuclear site has been demonstrated by the spontaneous assembly of [Fe20(02CR)2L2] (13) from ferric salts in the presence of water, an alkyl carboxylate salt, and a tridentate nitrogen donor ligand L that can cap an octahedral face on iron (8). Suitable ligands include tris(pyrazolyl)borates and 1,4,7-triazacyclononanes. Structure (13) is in essence a portion of the basic ferric acetate structure. The complexes are excellent physical and structural models of the diiron sites and model some aspects of reactivity including redox activity and interconversion of the oxo and hydroxo bridge. 

Chaudhuri, P., and Wieghardt, K. The chemistry of 1,4,7-triazacyclononane and related tridentate macrocyclic compounds, Prog. Inorg. Chem. 35 (1987), 329-436. 

Diebold, A., Elbouadili, A., and Hagen, K.S. Crystal structures and solution behaviour of paramagnetic divalent transition metal complexes (Fe, Co) of the sterically encumbered tridentate macrocycles l,4,7-R3-l,4,7-triazacyclononane coordination numbers 5 (R = i-Pr) and 6 (R = /-Bu), Inorg. Chem. 39 (2000), 3915-3923. 

Among unsolvated organolithium compounds only the alkyllithiums are soluble in noncoordinating solvents such as alkanes and arenes. Their states of aggregation depend on the structure close to lithium. Thus primary, tertiary and secondary alkyllithiums, all unsolvated, assemble into respectively hexamers, tetramers and equilibrium mixtures of hexamers and tetramers. Most organolithium compounds dissolve in and coordinate with donor compounds such as ethers and tertiary amines. The actual structures depend critically on the nature of the donor. Thus, diethyl ether solvates tend to be mainly cubic tetramers (with some dimers) while THF favors mixtures of monomers and dimers. Tertiary vicinal diamines such as TMEDA and 1,2-di-Af-piperidinoethane, DPE, favor bidentated coordinated dimers. Finally, in the presence of triamines such as pentamethyl-triethylenediamine PMDTA and l,4,7-trimethyl-l,4,7-triazacyclononane TMTAN, many organolithium compounds form tridentately complexed monomers. 

An extensive review of the thermodynamic aspects of polyaza macrocycles has been reported. Other reviews include the chemistry of tridentate and pentadentate aza macrocycles, 1,4,7-triazacyclononane and derivatives, and polyaza macrocycles with pendant chains. In general, the polyaza macrocycles form extremely stable complexes with transition metals of the later transition series, bnt show rednced affinity for alkali and alkaline earth metal ions compared to the oxa macrocycles. 

Porphyrin derivatives of Tl have been prepared the metal ion lies 0.9 A above the N4 plane, with an anion coordinated as the fifth ligand. A T1 L2 species is formed with 1,4,7-triazacyclononane two tridentate hgands are coordinated to a Tl ion in a distorted octahedron. It is an inert species with no additional labile coordination sites, and can therefore only be reduced via an outer-sphere electron-transfer process. Crown ether complexes are known only for R2TI salts. ... 

Chaudhuri, Phalguni and Wieghardt, Karl, The Chemistry of I,4,Triazacyclononane and Related Tridentate Macrocyclic Compounds.. . Chaudhuri, Phalguni, and Wieghardt, Karl, Phenoxyl Radical Complexes. Chei, Woo Suk and Suh, Junghun, Peptide- or Protein-Cleaving Agents Based on... 

Complexes of rhodium(III) with polydentate nitrogen ligands can also be prepared. Tridentate diethylenetriamine (22) forms [Rh(dien)2]l3 when allowed to react with rhodium trichloride in the presence of Nal. The trichloride salt can be obtained by metathesis with AgCl. The reactions of 1,4,7-triazacyclononane inorganic complexes are of current interest (Scheme 15). ... 

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